The massive investigation which swung into action after the bombing at the Boston Marathon appears to be making headway. But it's not been without its problems - dozens of news outlets in the US reported, incorrectly, that a suspect had been arrested and would appear in court. What is certain is that videos and pictures from spectators are playing a critical role in the investigation and have helped the FBI.

Transcript

TONY EASTLEY: The massive investigation which swung into action after the bombing at the Boston Marathon appears to be making headway.

But it's not been without its problems - dozens of news outlets in the US reported, incorrectly, that a suspect had been arrested and would soon appear in court.

What is certain is that videos and pictures from spectators are playing a critical role in the investigation and have helped the FBI.

In Washington there's been a security scare at the White House. We'll hear more of that from our reporter there shortly.

But back to Boston, it's all been unfolding over the last few hours. North America correspondent Lisa Millar is in the city.

Lisa, good morning. How advanced do you believe this investigation is now?

LISA MILLAR: Well the police commission Ed Davis was asked what was happening and he said they're working hard, there's a lot going on. Officials have been suggesting that they are making substantial progress. It's believed that they have been able to piece together different bits of video from the scene of the bombing and use that to have some idea of a suspect, some idea of someone that they want to talk to.

It's also been reported and not disputed that a lid from a pressure cooker which is understood to have made up the bomb, or at least one of them, was found on a roof nearby so they are now checking that for any latent fingerprints that there might be.

There's a sense they're making progress. The FBI were due to brief four hours ago, then it got delayed. Now it's been delayed again. There's an expectation that they will have something significant to share. What it might be, we do not know.

TONY EASTLEY: It's understandable Lisa I suppose that people want a quick result. Do you think that was what led to the unhelpful speculation earlier?

LISA MILLAR: Oh there was so much conflicting information. Certainly two news outlets were reporting with absolute certainty, including a description of the man, that there had been an arrest and that in fact someone was about to make an appearance at Federal Court.

Hundreds of media crews turned up there. Many of them just waited outside even after the denials that there had been an arrest.

In fact, it went as far up the tree as the federal attorney-general who had to say there has been no arrest. It was widely reported the FBI put out a denial and then delivered a warning to the media that it had to exercise caution and attempt to verify information through appropriate official channels and it warned that there could be unintended consequences by this kind of reporting. But Tony, it was a very confusing few hours this afternoon.

TONY EASTLEY: For the benefit of our listeners what absolutes do we know so far Lisa?

LISA MILLAR: The absolutes are that there aren't a lot of absolutes I'm afraid. They have a massive amount of information, photos, videos from a department store across from the bomb site. They've had agents going to the airport asking people for their mobile phone videos before they fly out and leave town. The forensic experts are at work there just doing these emu parades of the site.

The crime scene is shrinking. It is now only five blocks long and that's another idea that they are making progress. But there does seem to be a person that they have in mind but just how advanced they are with identifying who that person is, is unclear.

TONY EASTLEY: I suppose there in Boston people are trying to get on with their lives but I imagine there are constant reminders that set them on edge.

LISA MILLAR: Yes, hospitals have been evacuated, the Federal Court was evacuated after a bomb scare and in fact that's why we're being told that the FBI press conference has been postponed even though it was being held at a completely different venue.